Signal transmitter



March 23 1926. 1,577,634

F. E. DETMERS SIGNAL TRANSMITTER Filed March 20, 1924 Z3 7Jl// 777 layer 26 INVEN TOR.

Hm f. flf/mers BY M W 64 A TTORNEYS A a a I titan eaten the.

FRED E. DETMERS, 033 L055 ANGELES, CALIFGRHIA, ASSIGNOR TO LEW'IS DEGEN', 0F

PASADENA, CALIFOREIEA.

SIGNAL TRANSMITTER.

Application filed March 20, 1824. Serial No. 700,581.

To all whom 2'25 may concern:

Be it known that I, Fnnn E. DETMERS, a citizen of the United States, and resident of Los Angeles, in the county of Los Angeles and State of California, have invented new and useful Improvements in a Signal Transmitter, of which the following is a specification.

This invention relates to asignal transmitter employed to transmit electrical impulses along a circuit to a receiving station. Such devices are used in fire alarm telegraph systems, and the present invention will be described as embodied in such a system. The signal transmitter herein described is in tended for connection in series with a receiving or central station. In the normal operation of the type of system herein described the signals are transmitted through a closed metallic circuit, or loop, but, in case of a break in the circuit, may be operated through the ground and part of the loop.

In an electric si nal system employing the series closed circuit, the box comprising the signal transmitter or current interrupter will function only when the circuit is kept closed on all other parts of the loop. Therefore, in signal transmitting systems of the type above described, a ground connection at each box is employed to complete the circuit, in case the metallic loop is broken. In such a system, some provision must be made to open the ground connection when the signalling operationhas been completed.

In systems employing a plurality of boxes, non-interfering devices are used in each box so that should two or more boxes be operated at the same time, one box will automatically select and transmit itssignals without interference from the other boxes. If two or more boxes are pulled at about the same time, one box will transmit its round of signals while each of the other boxes pulled will be grounded through its respective ground connection but will nettransmit signals. A transmitter has been constructed using "two or more contact devices for the purpose of making and clearing the ground connection. Such a transmitter is illustrated in Patent No. 1,196,732, for signal transmitting device, granted AugustQQ, 1916, to L. Degen.

The primary object of this invention is to provide transmitter or box with a ground connection which will be kept open except when the box obtains control of the line and having a single contact device for the purpose of making and clearing the ground connection. This is accomplished by making both contacts of the contact de vice relatively movable. The ground connection is closed only when both contacts are in their proper position.

These objects together with other objects and corresponding accomplishments are obtained by means of the embodiment of my invention illustrated in the accompanying drawing, in which:

Fig. 1 is a front elevation of my improved fire alarm box, the casing and parts of the mechanism well known in the art being omitted to better illustrate the invention; Fig. 2 is a view similar to Fig. 1 showing the parts in position making the ground connection; Fig. 3 is another view showing the ground connection cleared by the n0n-inter :t'ering armature lever; Fig. 4: is a section as seen on the line t4= of Fig. 1, and-Fig. 5 is a wiring diagram of a series circuit ineluding fire alarm boxes which may be equipped with my improvement.

Referring more particularly to the draw ing, the fire alarm box shown is in general of a well known type employing a character wheel and key breah which is operated to open and close the circuit thereby sending electrical impulses which actuate a receiver at the central station. The boxes are of the. non-interfering succession type and in addition inf'lude'a ground branch circuit so that branch. and the ground at the central station. Such a system is shown in Fig. 5. Referring more particularly thereto, the di on shows a system having a battery ot cells A, tothe terminals of which are connected conductors B and C leading to registers E) and E. Fire alarm boxes F, G, and

H. are connected in series in the circuit.

in case of a break in the metallic loop, the

:es may operate through their ground.

nect in the ground. I have, however, only shown the essential parts of an operative system and for illustrative purposes only. The box shown herein contemplates the use of a signal transmitting train, which acts upon a shaft 5 and gearing connectingit with a shaft 6 tending to rotate the gears in the direction of the arrows. Upon shaft 6 is mounted a character wheel 7 of the type common in fire alarm systems and having teeth which move a key lever 8 and thereby make and close the circuit through the key break, later described. A trip lever 9 which is pulled to set the box in operation is indicated in section. The portion of the trip lever is so disposed that it underlies the stop lever 10 and by pulling the box the lever 10 is raised. Mounted upon the shaft which at all times tends to rotate, is a stop wheel 11 provided with a cam 12 which extends laterally from the wheel. The cam is of ring form and provided at diametrically opposite points with notches 13 and 14. Stop lever 10 carries a cam follower 15 having a curved under surface which is dc; signed to cooperate with the can] 12. The follower 15 when the stop lever is lifted by the trip lever and the stop wheel rotates will ride upon the outer peripheral surface, the stop lever 10 being held in its upper posi' tion. If the stop lever is free to move downwardly, it will drop to its lower position when follower 15 registers with either slot 13 or 14.,

One side of the transmission line passes through one of a pair of non-interfering coils16 to one of a pair of spring leaf contacts 17. The other side of the line passes through the other non-interfering coil to the other contact 17.. The contacts 17 are mounted side by side on an insulation block 18. The circuit may be made by a spring leaf contact 19 mounted upon the lower face of insulation block 18 and tensioned to tend to keep contact 19 out of engagement with the contacts 17. Contacts 1'? and 19 form what is hereafter called a signal key. lVhen contact 19 is engaged with the contacts 17,

it bridges the latter and closes the circuit. Forming an electrical extension of contact 19 is' a metallicspringlinger 20 disposed so that it may be engaged with a contact point 21 on the stop lever. The frame work and gearing of the transmitter is grounded in any suitable manner, such a ground being indicated conventionally by 22, see Fig. 1. When spring finger 20 is engaged with con-- tact 21, as shown in F 2, the contact 19 isgrounded. 1f the metallic line is complete, operation of the key break will cause signals to be transmitted. During the closure of the key break, current passes from one side of the line through one of the noninterfering coils to the key break and then.

through the other coil to the other side of the line thereby energizing both coils for a purpose later described. 1f the line is broken or open on one side, current will flow from the other side to the key break, to the ground and back to the station. In the travel of the current itpasses through one coil and energizes the latter thereby insuring the energization of the non-interfering coils.

The non-interfering coil 16 has an armature lever 23 pivoted at 2 1, which is secured to a tension spring 25 tending to maintain the armature away from the coil 16. The number of ampere turns on the non-interfering coil is so selected tl at the intensity of the magnetic field when the coil is energized is sutlicientto hold thearmature lever 23 to the pole of the coil, but is insufficient to draw the lever from its furthermost position in which position spring 25 tends to hold it. Mounted upon the armature lever is a roller 26 of insulating material arranged to engage the finger 20 at a hump thereon. The swinging of the armature lever will cause the linger to be moved to and from contact lug 21. Key lever Sis pivoted at 27 and is provided with afollower 28 which rides upon the character wheel periphery. It has an insulated post 29 to engage spring contact 19 and move the latter into opening and closing position with contacts 17. An extension 30 of key lever 8 has an end arranged to be disposed behind the pintle for roller 26 when armature lever 23 is in closed or attracted position as shown in Fig. 2. When lever 8 is resting upon the top of the teeth on the character wheel, the circuit is closed through contacts 19 and 17, and if the loop is complete, both non-interfering coils 16 are energized. The armature lever will then be held to the pole of the non-interfering coils. lVhen the lever 8 rests at the bottom of the tee h on the character wheel, the circuit is open by reason of contacts 19 and 1'7 being out of engagement. At the time the coils 16 are deenergized, the armature lever 23 would be pulled away from the pole by spring 25, but for the extension 30 which prevents the movement by reason of being. disposed behind the pintle of roller 26.

Armature lever 23 has a pin 31 projecting therefrom and is disposed to be engaged by the end of stop lever 10, as shown in Fig.1. The stop lever is formed with a shoulder 32 and a cam surface 33 against which pin 31 may rest, see Fig. 3. The cam surface is such that the stop. lever in dropping from the position shown in Fig. 3 to that wherein shoulder 32 engages pin 31, armature lever 23 will be swung to bring the armature thereof toward the coil 16.

.Armature lever 23, has a tail 3 1 provided with a lateral. ledge it) on the rear. A pin 35 is mounted upon the wheel 36 fixedly secured to shalt 6. This pin is arranged to engage the ledge 40 upon the rear side of tail 34, except when the armature lever iseithcr against the pole as shown in Fig. 1

or in its outermost position so the pin clears.

the tail as shown in Fig. 3. If the lever 23 is moved a slight amount from its outermost position, the pin 35 as it moves upwardly will engage the ledge 40 and move the lever with its armature against the coil. The movement of lever 23 is caused by the dropping oi stop lever 10, an amount sullicient to throw the tail 3% with its ledge lO into the path of pin 35. When the lever 23 is in position with the armature away from the coil 16, the ledge 40 is moved to the right so that pin 35 will pass to the left of the tail, see Fig. 3.

Lever 8 has a tail 37 arranged so that a pin 38 on stop wheel 11 may pass behind it. At the end of the tail is a rearwardly projecting ledge ell arranged so that it will be in the path of travel of the pin 38 when the key lever 8 is in its lower position.

The box operates in the following manner: In normal inoperating position of the box, the parts are in the position shown in Fig. 1. Suppose the trip lever 9 is pulled, raising stop lever 10 into train release position. Follower is lifted from cam slot 1 L thereby releasing stop wheel 11 and the signal transmitting train starts. Lifting of the stop lever disposes the end thereof so that pin 31 is released and armature lever 23 may be swung by spring 25 away from the armature pole of coils 16, unless the latter are energized. Pin 38 on stop wheel 11 engages tail 37 and holds contacts 19 and 17 in closed position. "if no other box is sending signals, the non-interfering coils will be energized and hold armature lever 23 in line control position. Pin 33 finally rides out of ei'igagement with the lodge on tail 3'? of the key lever and the latter drops into the indentaticns on the character wheel. In dropping, the end 30 disposes itself behind the pintle on roller 26, thereby preventing spring from pulling the armature lever away from the pole, the coils at that time being deenergizeil due to the contacts 19 and 17 being opened. Roller 26 in the position of armature lever 23 just described maintains spring finger 20 in its lower position and contact point 21 is engaged therewith, see Fig. 2. Thus, the circuit is grounded at the box. Suppose the box is pulled while another box has control of the line. Then the non-interfering coils are being intermittently energized by t c impulses being sent from the other box, and armature lever 23 will be pulled away from the pole by spring 25 into line release position. This disposes roller 26 beneath extension 30 on lever 8 preventing the latter from openlng the circuit and thereby transmitting signals. It also moves the roller 26 so that linger 2O rises and disengages contact point 21, thereby clearing the ground, see Fig. The box is designed to make'tour rounds and then try for the line without sending a signal. Suppose the box in control of the line releases it. As slot 13 in the cam 12 registers with the follower 15, the latter starts to drop therein, a slight movement. being permitted by pin 31 engaging shoulder 32 on lever 8. The movement causes the cam 33 to engage pin 31 and to swing tail 34 on lever 23 into the path of pin 35 Which completes the movement of the armature to the pole. At the same time, pin 38 engages tail 37 and lifts lever 8 to close contacts 19 and 17. The non-interfering coils are then energized and the pull of the pole draws the armature lever to it and holds the latter. The under surface of cam follower 15 is curved so that the follower will ride out of the slot 13, it only being lowered a slight degree, shoulder 32 r sting on pin 31. The swinging of armature lever 23 to closed position will cause roller 26 to move spring contact 20 downwardly into engagement with contact 21. After the box has taken control, signals are sent and the ground is maintained. When slot 1 1 in cam 12 registers with follower 15, the latter is free to drop and'lever 10 drops downwardly, moving contact point 21 away from spring finger 20 thereby clearing the line. Suppose there is a break in the line on one side of the box pulled. The train andparts of the box are set in: operation as before with the following differences: Current flows from the un-' broken side of the line through the nonintertering coils 16 011 that side, toa contact 17, to contact 19, through spij'ing'finger 20 and contact 21 to the ground and thence to the central station. The key. break makes and breaks the contact so that through the'grounded connection a signal is transmitted. The non-interfering coil through which current passes is energized sutlicie'ntly to cause the armature lever 23 to function in proper manner. Assume a box on the unbroken side of the line has control. The controlling box is grounded and no current will pass to the box pulled, it it is between the controlling box and the break. The non-interfering coil will not be energized until the controlling box releases the line. It the controlling box is 'betweenthe pulled box and the break, the operation of the pulled box is the same as in the case of an unbroken line first described.

It will be noted that one side of the ground contact is a spring which is actuated by the non-interfering armature lever, but is insulated therefrom. The lever has two positions and the spring likewise has two positions. One position is the make position, that is, when the armature is held to the pole either.mechanically or magnetically. The other position is the break positionwhen the armature lever is away from the pole of the coil in line release position. The other side of the contact is partof the stop lever and also has two positions. One is the make position which is that when the stop lever is in train release position and the other is the open position, that is, when the lever is in the, train lock position. There is one contact device for the purpose of making and clearing the ground connection. This contact has two relatively movable contacts.

What I claim is: i

1. In a non-interference ground connec tion transmitter, the combination of a sig nal transmitting train having a stop and starting means, a signal key, means actuated by said train to operate said key, a ground connection comprising a control switch having a pair of relatively movable contacts, non-interfering means to maintain said key closed during movement of said train at the tripping of the latter, said, noninterlering means having an actuating membervto cause one of said movable contacts to be moved to break position upon said non-interfering means being in line releas ing position and to be moved toward make position upon said non-interfering means being in line control position, the other of said movable contacts being positioned by said stop means in make position when said stop means is in train releasing position and in break position when said stop means is in train stopping position.

2. In a non-interference ground connection transmitter, the combination of a signal transmitting train having a stop and starting means, a signal key, means actuated by said train to operate said key, a ground connection comprising a control switch having a pair of relatively movable contacts, one of said contacts beingla spring finger normally tensioned for break position, non-interfering means to maintain said key closed during movement of said train after tripping of the latter, said non-interfering means having an armature lever, a projection on said lever arnnged to engage said spring finger and move the latter into make position upon said leverbeing held in line control position, the other of said movable contacts being positioned by said step means in make position when said stop means is in train releasing position and in break position when said stop means is in train stopping position.

3. In a non-interference] ground connection transmitter, the combination of a signal transmitting train having a stop and starting lever, 21- signal key, means actuated by said train to operate said key, a ground connection comprising a control switch having a pair of relatively movable contacts, noninteri'ering means to maintain said key closed during movement of said train after tripping the latter, said non-interfering means having an actuating member to cause tion transmitter, the combination of asignal transmitting train having a stop and starting means, a signal key, means actuatedby said train to operate said key, a ground control switch having a pair of relatively movable contacts, nonnnterl ering means to maintain said key closed during movement of said train after tripping of the latter, said non-interfering means having an insulated actuating member to cause one of said movable contacts to be moved to break position upon said non-interfering means being moved into line releasing position and to be moved into make position upon said nonintcrl ering means being in line control position, the other of said movable contacts comprising a contact point, on said stop means positioned in make position when said stop means is in train releasing position and in break position when said step means is in train stopping position, said stop means being grounded.

5. In a non-interference ground connection transmitter, the combination of a sig lflll nal transmitting train having a stop and starting lever, a signal key, means actuated by said train to operate said key, a ground control switch having a pair of relatively movable contacts, non-interfering means to maintain said key closed during movement of said train after tripping of the latter, said non-interfering means having an insulated actuating member to cause one of said movable contacts to be moved to break position upon said non-interfering means being moved into line releasing position and to be moved into make position upon said noninterfering means being in line control position, the other of said movable contacts comprising a contact point formed on said stop lever positioned in make position when said.

stop means is in train releasing position and l in break position when said stop means is in train stopping position, said stop lever being grounded.

6. In a non-interference ground connection transmitter, the combination of a signal newness transmitting train having a stop and starting lever, a signal key, means actuated by said train to operate said key, a ground control switch having a pair of relatively movable contacts, one of said contacts being aspring linger normallytensioned for breakposition, non-interfering means to maintain said key closed during movement of said train after tripping the latter, said non-interfering means having an armature lever, an insulated projection on said armature lever arranged to engage said spring linger and move the latter into make position upon said armature lever being held in line control position, the other of said movable contacts comprising a point on said stop lever positioned by said lever in make position When said lever is in train releasing position and in break position When said lever is in train stopping position, said stop lever being grounded.

In Witness that I claim the foregoing I have hereunto subscribed my name this 14th day of March, 192%.

FRED E. DETMERS. 

